The present embodiments relate to a head coil for a magnetic resonance tomography (MRT) system.
Magnetic resonance tomography devices for examining objects or patients using magnetic resonance tomography (MRT, MRI) are known, for example, from DE 10314215 B4.
In magnetic resonance tomography, images are conventionally recorded with a high signal-to-noise ratio (SNR) using coils (e.g., “local coils”). The coils are antenna systems that are mounted in immediate proximity on (anteriorly) or under (posteriorly) the patient. During an MRT measurement, the excited nuclei induce a voltage in the individual antennae of the local coil. The induced voltage is amplified with a low-noise preamplifier (e.g., LNA, preamp) and passed on via cables to the receiving electronics. In order to improve the signal-to-noise ratio, including with high resolution images, high-field systems are used (e.g., having field strengths of 1.5 T to 12 T and more). Since more individual antennae may be connected to an MR receiving system than receivers are present, a switching matrix (e.g., RCCS) is connected between the receiving antennae and the receiver. The switching matrix routes the currently active receiving channels (e.g., the channels that are currently in the field of view (FOV) of the magnet) to the receivers present. By this, more coil elements than receivers are present may be connected, since for whole-body coverage, only the coils that are in the FOV or the homogeneity volume of the magnet are to be read out.
The “coil” (or “local coil”) may be an antenna system that may include one or more antenna elements (e.g., coil elements, an array coil). The individual antenna elements may be configured as loop antennae (loops), or butterfly or saddle coils. A coil includes coil elements, a preamplifier, further electronics (e.g., sheath current filters) and cabling, the housing and may include a cable with a plug, by which the coil is connected to the MRT system. The receiver (RX) provided on the system side filters and digitizes the signal received by the local coil and passes the data on to the digital signal processing unit. The digital signal processing unit may derive an image or a spectrum from the measurement and make the image or spectrum available to the user for diagnosis.
In order to position patients with abnormal changes to the cervical spine, for example, ankylosing spondylitis, wryneck, round back, or trauma patients, in head coils, the head coils may be raised (e.g., tilted) in a posterior region of the head, since the patient is not able to place the head flat in the coil in this position. For contacting systems that provide a defined relationship between the patient support and the head coil, for example, with “direct” contacting (e.g., contacting by plugging in plugs for power supply and/or for data lines) of the head coil to the patient support or with alternative contacting variants such as capacitive coupling between the patient support and the head coil, movement of the coil relative to the patient support is not possible in the plugged-in condition (e.g., if contacts of the local coil are plugged into contacts of the patient support). The coil and the patient support form a fixed plugged-together unit.
For coils that directly contact the patient support or for alternative contacting possibilities having a fixed relationship between the patient support and the coil, in the case, for example, of ankylosing spondylitis patients, a possible solution is changing the position of the patient with suitable mounting materials (e.g., a higher support for the pelvis). A further alternative solution is the placement of wedge-shaped parts under the head coil.